Pressure-adhesive correction materials and method for producing same

ABSTRACT

Pressure-adhesive correction sheets and ribbons which carry a latent adhesive layer which has a surface which is not sticky to the touch but which becomes sticky in areas subjected to applied imaging pressure. The present materials are used for the impactremoval of erroneous images from a copy sheet, which images consist of complementary transfer composition applied by means of a complementary transfer element, including split imaging ribbons carrying both said complementary transfer composition and said latent adhesive correction composition.

O United States Patent 1191 1111 3,9

Brown et al. Dec. 9, 1975 1 PRESSURE-ADHESIVE CORRECTION 2,836,152 5/1958 Rosenblum 197/181 x MATERIALS AND NIE Q FOR 2,986,477 5/1961 Eichel 1 428/343 X 3,027,271 3/1962 Plasse et al. 428/346 X PRODUCING SAME 3,121,021 2/1964 Copeland 428/219 [75] Inventors: Albert E. Brown; Allan T. 3,189,581 6/1965 Hart et al.", 428/355 Schlotzhauer; Douglas A. New 3,330,791 7/1967 Mater et a1. 197/172 X ll f Gl Cove N Y 3,404,021 10/1968 Newman et al. 428/512 3,531,316 9/1970 Sternasty 428/346 X [73] Ass1gnee: Columbia Ribbon and Carbon 3,535,295 10/1970 Davis 428/346 X Manufacturing Co., Inc., Glen Cove, 3,650,794 3/1972 Steinbach 197/181 X N,Y, 3,664,869 5/1972 Sala et al. 197/172 X 3,724,633 4/1973 Korb et a1 197/181 X ,[22] Filed: Nov. 22, 1974 211 App], 52 27 Primary Examiner-Edgar S. Burr Assistant ExaminerR. E. Suter Related Apphcatmn Data Attorney, Agent, or Firm-Thomas L. Tully; Arthur A. [63] Continuation-impart of Ser. No. 439,395, Feb. 4, Johnson 1974, abandoned.

[52] US. Cl. 197/172; 197/18l; 427/207; [5.7] ABSTRACT 428,261 Pressure-adhesive correctlon sheetsand ribbons WhlCh 51 int. c1. B41J 31/05 carry a latent adheswe layer whch a Surface 58 Field of Search 197/172, 181; 427/140, which is Sticky the much but whlch bemmes 427/141 207, 372; 428/260I 261, 343, sticky in areas subjected to applied imaging pressure. 3 46 3 49 352 355 512414 The present materials are used for the impact-removal of erroneous images from a copy sheet, which images [56] References Cited cpnsiistt) of complfementaqi transfer compositilon app 1e y means 0 a comp ementary trans er e ement, UNITED STATES PATENTS including split imaging ribbons carrying both said 1,183,424 5/1916 Baldwin 197/181 complementary transfer composition and said latent 2,572,458 10/ 1951 Eustis 428/355 adhesive correction composition 2,575,265 11/1951 Fiedler et al 428/343 X 2,576,968 12/1951 Pike et al 428/346 x 24 Claims, 5 Drawing Figures US. Patent Dec. 9, 1975 3,924,728

PRESSURE-ADHESIVE CORRECTION MATERIALS AND METHOD FOR PRODUCING SAME This application is a continuation-in-part of applica tion Ser. No. 439,395, filed Feb. 4, 1974 and now abandoned. 7

Several methods are known for the correction of typed errors. The most common method, other than using rubber erasers, is the masking method whereby the erroneous image is overstruck using a white transfer composition which transfers to the surface of the erroneous image and blends with the white color of the paper to mask the erroneous image from view. Thereafter the correct image is typed over the masked image. The masking method is unsatisfactory in cases where the copy paper is other than white and also in cases where the copy paper or sheet is highly translucent or is transparent. Also in cases where the copy sheet is reproduced by methods such as infrared duplication, the masked erroneous image may be duplicated on the copy together with the correct image as an illegible combined image.

Another method proposed years ago in Baldwin U. S. Pat. No. 1,183,424 and more recently in Korb et al US. Pat. No. 3,724,633 (IBM) relates to the use of an adhesive ribbon to pick erroneous typed images from a copy sheet. The method is in current commercial use and is similar to the masking method to the extent that the crroneous image is overstruck using the appropriate type key. However, instead of interposing a ribbon carrying a transferable masking coating, one interposes a ribbon carrying a sticky adhesive coating, similar to Scotch tape. The sticky ribbon is retained spaced from the copy sheet to be corrected except in impressed areas which adhere to the erroneous image and lift the erroneous image from the copy sheet when typing pressure is released. Thereafter the correct image is typed in place of the removed image. Preferably this method is used in association with imaging compositions which are dry and substantially free of oils and dissolved dyes which can migrate into the copy paper and stain the paper fibers.

While such adhesive correction ribbons are in current commercial use, they do not present important problems. Such adhesive ribbons must be mounted on special spools and tensioned and moved using special mechanisms which must be built into the typewriter in addition to the spools and mechanisms present in every typewriter for the support and movement of the imaging ribbon. Thus a special typewriter is required. Also, it is not possible to use such adhesive coatings on conventional split correction ribbons in place of the masking coating, such as in the ribbons of US. Pat. No. 3,664,869, because it isnot possible to evenly wind a ribbon on a spool if one-half the width of the ribbon is sticky and the other half is not. Also, the sticky half of the ribbon will tend to stick to the conventional ribbon guides, the uneven amount of tension required to pull the sticky and non-sticky halves of the ribbon from the spool will cause breakage of the ribbon, andunlessthe ribbon is rewound perfectlyeven on the take-up spool, the sticky half of the ribbon will overlap with portions of the imaging half of the ribbon and will pull the latter from the foundation when the ribbon travel is reversed for reuse.

Finally, it is not possible to use such sticky adhesive coatings on correction tabs or sheets of the type used will not adhere to itself but which is capable of being rendered sticky and adhesive by the application of imaging pressure thereto, such as typing pressure.

It is another object of this invention to provide cooperative elements adapted for cooperate use, one element comprising a pressure-sensitive transfer element carrying a transfer composition and the other element comprising a correction element having a latent adhesive composition adapted to remove images formed from such transfer composition under the effects of typing pressure.

It is still another object of this invention to provide a novel split imaging ribbon, one-half the width of which is coated with a special imaging composition and the other half width of which is coated with a complementary latent adhesive composition adapted to remove images produced with said imaging composition from a copy sheet under the effects of typing pressure.

It is a preferred embodiment of the present invention to provide latent adhesive correction materials which are sufficiently translucent or transparent so that an erroneous image to be removed thereby can be viewed therethrough by the typist to insure proper alignment during the correction process.

These and other objects and advantages of the present invention will be apparent to those skilled in the art in the light of the present disclosure including the drawing, in which:

FIG. 1 is a diagrammatic cross-section, to an enlarged scale, of an imaged copy sheet and a correction element superposed under the effect of typing pressure,

FIG. 2 corresponds to FIG. 1 but shows the sheets separated after the release of the typing pressure, the impressed center images remaining adhered to the correction element after having been lifted off the copy sheet,

FIG. 3 is .a plan view of a section of a split imagingcorrection ribbon produced according to one embodiment of this invention,

FIG. 4 is a diagrammatic plan view of a word on a copy sheet containing an erroneous letter m, and a correction tab, produced according to another embodiment of this invention, held in position over the erroneous image preparatory to the application of typing pressure, and

.FIG. 5 corresponds to FIG. 4, but shows the elements separated after the application of typing pressure, the erroneous image m being removed from the copy sheet and being adhered to the underside of the correction but which is capable of being displaced, penetrated or otherwise combined with and dominated by the adhesive material under the effects of applied pressure. Thus the coated sheet material has a latent adhesive surface which is not sticky or adhesive to the touch or under normal handling pressures but which is capable of becoming sticky or adhesive at ambient temperatures in desired areas by the application of imaging pressures, such as typing pressures, to such areas. The present materials preferably are produced as continuous sheet materials which subsequently are cut into sheet lengths, ribbons, tapes, tabs or other sizes depending upon the manner in which the materials are to be used.

The latent adhesive correction materials of the present invention are produced by the application of a single layer to a flexible foundation, said layer containing both the normally tacky soft resinous adhesive base material and the non-sticky surface material and having the ability of drying or solidifying as a layer in which the exposed surface consists primarily of the particulate non-sticky surface material which prevents the underlying latent adhesive material from coming into contact with the hands or with other sheets in the absence of applied imaging pressure. Under the effects of such pressure, the latent adhesive material is forced around or through the surface material for adherence to the surface against which it is impressed.

The drawing illustrates the use of the present sheet materials as image correction materials in different forms.

Referring to the drawing, FIG. 1 illustrates an imaged copy sheet and a pressure-adhesive correction sheet 20 superposed under the pressure of a type bar 30. The copy sheet 10 consists of a flexible paper or plastic film sheet 11 carrying solid images 12 and 13 which have been typed thereon using a filmor paper-base typewriter ribbon coated with a solvent-applied solid dry transfer composition. The correction sheet 20 consists of a flexible paper or plastic film sheet 21 carrying a pressure-adhesive layer 22. The pressure-adhesive layer 22 might be termed a stratified layer in which the soft resinous adhesive base material is present primarily in a base stratum adjacent the flexible foundation 21 while the surface stratum consists primarily of protrusions of non-tacky surface material such as inert resinous microspheres.

The type bar 30 carries an image type face corresponding to the erroneous center image 13 to be removed from the copy sheet 10. Under activation of the appropriate type key, bar 30 strikes the rear surface of correction sheet 20 and produces an imagewise pressure contact between sheets 20 and 10, said contact being limited to the area of center image 13 and the corresponding area of the pressure-adhesive layer 22. Some of the soft tacky adhesive of the base stratum is compressed and exuded through or beyond the nontacky surface stratum in the impressed area to provide a sticky adhesive surface in pressure contact with the center image 13. In the non-impressed areas, the other images 12 are in normal surface contact with the nontacky surface stratum and do not adhere thereto.

When impact pressure is relaxed by withdrawal of the type bar 30 and the sheets 10 and 20 are separated, the center image 13 remains bonded to the correction layer 22 on the correction sheet 20 and is cleanly lifted off the copy sheet 10, as illustrated by image 13X in FIG. 2 of the drawing. The copy sheet 10 can now be reimaged in the appropriate area to substitute a correct image for the erroneous image 13 which has been removed.

FIG. 3 illustrates a split imaging-correction ribbon 35 having lengthwise stripes of pressure-adhesive correction composition 31 and complementary pressuretransferable imaging composition 32 which is specially formulated so as to be cleanly removable from a copy sheet by means of said correction composition. The ribbon 35 has a flexible foundation, preferably a plastic film, and the stripes 31 and 32 preferably are applied to the foundation as solutions using appropriate volatile solvents and appropriate printing rollers. On drying by evaporation of the volatile solvent, the correction stripe 31 forms a non-tacky surface stratum of nontacky inert surface particles 33. Alternatively, one or both of the stripes 31 and 32 may be produced on a separate foundation and cut and adhered on a common foundation to produce the structure illustrated by FIG. 3.

FIGS. 4 and 5 illustrate the use of a correction sheet 4( in tab form to remove an incorrect image 51 from a copy sheet 50 carrying correct images 52. The tab 40 comprises a clear, flexible plastic film foundation 41 and the correction layer on the underside thereof contains clean adhesive and projecting, non-tacky inert surface particles 42 whereby the tab 40 is sufficiently translucent or transparent that the underlying image 51 can be clearly viewed therethrough to insure proper positioning of the tab 40 against the image 51.

When the m key is activated on the typewriter, the tab 40 is pressed imagewise against the image 51 and adheres to and lifts the image 51 from the copy sheet 50 when the tab 40 is removed from the copy sheet 50.

The other correct images 52 remain on the copy sheet 50.

As mentioned supra, the pressure-adhesive correction materials of the present invention comprise a flexible foundation such as paper or plastic film carrying a unitary latent adhesive correction layer. The foundation preferably is one which does not absorb the correction layer to any substantial degree. Thus, less porous papers and treated papers such as glassine paper are preferred while normally porous papers having a resinous barrier layer supporting the correction layer are also suitable. Clear plastic films are preferred for some applications because of their strength, pressuredeformability and transparency and impervious nature. Resinous undercoatings may be used to bond the correction layer to the film foundation where necessary. Preferred films are polyethylene terephthalate polyester, polyethylene, polypropylene, cellulose acetate, nylon, and the like, depending upon whether sheets, ribbons or tabs are being produced. Generally the paper foundations are preferred for correction material sold in continuous tape form in a conventional correction tape dispenser provided with means for facilitating the tearing of desired lengths from the continuous tape since paper tears more easily than plastic films. However, plastic film foundations may also be used for continuous tapes provided that a suitable cutter is used on the dispenser, such as a metallic tearing means. On the other hand, plastic films are generally preferred as foundations for correction material sold and used without tearing, i.e. as ribbons, individual full sheets or tab sheets, or the like, where strength and durability are important.

According to a preferred embodiment, the present correction materials are provided with a cushioning foundation which has a thickness greater than normally used to produce pressure-sensitive transfer sheets. The object is to accomplish a result which is to be avoided with ordinary transfer sheets, i.e. a broadening of the impact pressure whereby the area of the pressure-adhesive composition which is activated against the image to be corrected by removal isgreater in all directions than the area of the image itself. This insures overlapping coverage of the image to be removed and complete removal thereof. Such cushioning foundations include paper or plastic film of increased thickness, i.e. from 1.5 to 5 mils, laminates of paper and/or plastic films united by a resinous bonding layer, paper and/or plastic films having a soft resinous binder layer either between the film and the pressure-adhesive correction layer or as a back coating on the film, or the like. This result is also accomplished to some extent by the soft, pressure-flowable properties of the pressure-adhesive composition itself.

The correction composition is based upon a conventional soft resinous binder material which contains at least about by weight, based upon the total weight of the adhesive layer, of one or more soft, pressureflowable, tacky or sticky adhesive resins. The preferred adhesives are the viscous liquid elastomers such as the polybutenes, polyisobutylenes, polyisoprenes, polyvinyl ethers, polybutadiene and rubbery copolymers of butadiene with acrylonitrile, styrene and other monomers, rosin esters, and the like. Most preferred are the lndopol polybutenes having mean molecular weights ranging from 320 for lndopol L-lO to 2150 for lndopol H-l900, and the Vistanex isobutylene polymers having mean molecular weights of from 8700 to 11,700.

In addition to the highly adhesive resinous material, the present compositions preferably contain, as an extender or diluent, a synthetic resinous binder material or a wax binder material which is substantially less adhesive than the adhesive resinous material, i.e. it is not sticky or adhesive or is less sticky or adhesive than the adhesive resin and is compatible therewith, at least at elevated temperatures, to provide a blend having the desired degree of tack or adhesiveness. Preferred extenders include resins such as the polyolefins including polyethylene and polypropylene, polystyrene, polyvinyl butyrate, nylon, acrylic polymers, and the like, and waxes such as camauba, montan, microcrystalline paraffin, beeswax, and the like. Most preferred for solventapplied compositions are the polyethylene emulsions such as Polyethylene A-C 6 which has a mean molecular weight of 2000 and a softening point of about 220 F. In the case of solvent-applied compositions, the extender resin or wax must be soluble in the same volatile solvent used to dissolve the adhesive resinous binder material, at least at elevated temperatures. In the case of hot-melt compositions, the wax extender and adhesive resinous binder material must be meltable together at elevated temperatures.

The present latent-adhesive resinous compositions also contain a substantial amount, at least about 10% by weight based upon the total solids content, of a nonsticky inert surface material which is a solid which is incompatible with the adhesive resin and with the extender wax or resin, if present, and is insoluble in the volatile solvent used as the coating vehicle or has a melting point in excess of the temperature of the hotmelt composition. The surface material contains at least 10% by weight of the particles thereof in the form of particles having a size at least slightly greater than the thickness of the dried adhesive correction layer in areas between said large particles, whereby said particles project above the general surface of the correction layer and assist in preventing the adhesive correction layer from sticking to the fingers or to other sheets in the absence of imaging pressure. Since the present correction layers generally have a mean thickness of from about 2 to 10 points (i.e. from 0.0002 to 0.001 inch) in areas between the projecting particles, then the surface material contains at least 10% and up to by weight of the particles thereof in the form of particles having a minimum size ranging from about 6 microns for a 2 point coating up to about 26 microns for a 10 point coating. The maximum particle size for a correction layer of any thickness appears to be about three times the mean thickness of the layer, i.e. from about 13 microns for a 2 point coating up to about 75 microns for a 10 point coating. Obviously the presence of small amounts of particles of larger size, or of agglomerates of particles having a larger size can be tolerated, and in fact most surface materials generally consist of a mixture of particles of various sizes even though they have a specified average particle size.

The preferred surface materials are spheres of polymers having an average particle size of from about 4 to 25 microns, at least 10% by weight of the particles of which have a diameter greater than the thickness of the adhesive layer in which they are used. Some such spheres also have a lower specific gravity than the resinous binder material, i.e. the adhesive resin or combination of adhesive resin and extender resin or wax, and this appears to assist their formation of a surface straturn. The present inert polymer spheres retain their spherical shape when dispersed in the solution or hotmelt composition containing the adhesive binder material and at least 10% by weight of the particles extend above the adhesive stratum of the dry layer due to their size. Other smaller particles may come to the surface of the layer during drying or cooling of the composition on its flexible foundation or are left at the surface of the dry layer when the solvent is evaporated or the composition cools and the resin binder shrinks on solidification. The most preferred polymer sphere composition is Polymist A 12 which comprises polyethylene spheres having an average sphere size of 12 microns (4.8 points), a melting point of 284 F, a specific gravity of 0.99 and containing about 40% by weight of larger spheres. Also suitable are Fluon F which comprises polytetrafluoroethylene spheres having an average sphere size of less than 5 microns (2 points), a melting point greater than 600 F and a specific gravity of 2.28, and Polymist 5 which is similar to Fluon F 170 and has an average sphere size of 4 microns (1.6 points) and a melting point of about 660 F. All of these materials, which contain at least 10% by weight of particles greater than the average size, are commercially availableas dry powders which have a whitish color and are readily dispersible in the solution of the correction composition. Generally, it appears that even the smaller polymer spheres are supported on each other in the pressure-adhesive layer so that at least a substantial number of the smaller spheres extend beyond the surface of the adhesive stratum and assist the larger polymer spheres in spacing the latter from contact with the hands or with adjacent sheets.

The weight ratio between the polymer spheres and the total solid composition may be varied depending upon the size and weight of the polymer spheres, the thickness of the correction layer, the degree of tackiness of the resinous binder material and the degree of pressure-sensitivity desired. In general, the polymer spheres comprise from about to about 50% I by weight of the total composition, the preferred range being from about to about 30% by weight. A thick correction layer can contain a greater ratio of adhesive resin and extender to inert non-tacky particles than a thinner correction layer since both have the same surface area to be protected. 7

In place of the preferred polymer spheres, it is also possible to use as surface materials similar amounts of other inert finely-divided, particulate materials which are non-sticky to the touch and which have the size requirements discussed supra so as to form a projecting surface stratum when the correction composition is applied to a flexible foundation and dried. Suitable are glass beads, silica spheres, hydrated amorphous silica particles, starch particles, clay particles, and the like. The weight ratio of heavier surface materials obviously will be on the high end of the aforementioned ratios, while the weight ratio of lighter surface materials will be on the low end of such ratios.

The thickness of the correction coating and/or of the foundation of the present invention is important in insuring its performance in accomplishing the complete removal of erroneous images. The coating and/or the foundation must be sufficiently thick that the adhesive binder is capable of being exuded beyond the nontacky surface material and of spreading at least slightly so as to overlap the erroneous image in all directions to insure its complete coverage and removal as discussed supra in connection with cushioning foundations. In this regard, it is also preferred to support the correction layer on a foundation which has good pressure deformability such as nylon, polypropylene or polyethylene. The thickness range will vary somewhat depending upon the smoothness and absorbency of the pressuredeform'able foundation but in general the thickness ranges from a minimum thickness of about 2 points (4 pounds per ream of 3300 sq. ft.) to a maximum thickness of about 10 points pounds per ream). The preferred thickness range is between 3 and 6 points.

The pressure-sensitive transfer materials used according to the present invention are preferably formulated so as to provide the best possible results when used in combination with the present correction materials, i.e. so as to be complementary thereto. It should be understood that the present correction materials are not suitable for the complete removal of all types of images. For instance, images formed on paper from liquid typewriter ribbon ink stain the paper fibers and cannot be completely removed. Also, images formed on paper or other receptive support from oil-containing hot-melt wax compositions such as by means of wax carbon paper or ribbon cannot be removed completely because the wax imaging composition has poor cohesion and fractures internally during removal rather than picking off as a whole and/or the oilpresent integrates with the paper and carries coloring matter therein.

The preferred pressure-sensitive transfer compositions used herein are solvent-applied compositions having a film-forming or resinous binder material and pig ment and which are dry, cohesive and essentially free of soluble dyes which can migrate into a paper support nyl acetate and styrene, acrylic resins such as ethyl acrylate and methyl methacrylate, chlorinated rubber, terpene resins, and the like. Improved frangibility is provided by using mixtures of such resins which are soluble in a common solvent but which are incompatible with each in the amounts used so that they separate from each other upon evaporation of the solvent, thus preventing excessively high internal bonding therebetween and promoting frangibility. In this connection reference is made to US. Pat. No. 3,404,021 which discloses suitable incompatible resinous binder mixtures. Generally, the resinous binder material comprises from 15% to 50% by weight of the transfer composition.

The pigment maybe any conventional solid colorant such as carbon black, milori blue, magnetic iron oxide, or the like, generally in an amount ranging between about 10% to 40% by weight of the total dry composition.

Oils, oleaginous semi-solid materials or waxes may be added to improve the frangibility of the transfer composition provided that sufficient porous filler is included to absorb any such materials which tend to migrate quickly from the transfer composition into the copy paper, as discussed supra. Thus, liquids such as refined rapeseed oil, mineral oil, butyl stearate, semisolids such as lanolin and hydrogenated oils, and waxes such as paraffin and carnauba can be incorporated in amounts ranging from 0% up to about 40% provided that porous fillers such as clay, talc, calcium carbonate, diatomaceous earth, silica or starch preferably are included in substantially similar amounts to absorb such materials.

The following examples are given as illustrative and should not be considered limitative.

EXAMPLE 1 A latent adhesive correction element is produced by coating a web of 2.5 mils thick polyethylene terephthalate polyester film with about 24 pounds per ream (3300 sq. ft.) of the following composition:

Ingredients Parts by Weight Polyethylene AC 6 7 Polybutene H 300 7 Stabelite Ester l0 3.5 Polymist A 12 7 Naphtholite solvent 75.5

rest of the solvent is then added and the solution is cooled to room temperature. During cooling, the solution passes through a cloud point and turns white and increases in viscosity due to at least a portion of the polyethylene resin coming out of solution. Next the Polymist A 12 (registered trademark for polyethylene resin spheres) is added to the solution with agitation to form a uniform mixture which is coated onto the polyester film.

The coated film is heated to a temperture of about 185 F to evaporate the solvent and form a dry layer. The coated film has a frosted appearance but is translucent and transpicuous, i.e. images positioned against the coated film are clearly legible therethrough. The dry layer has a weight of about 6 pounds per ream .(about 3 points) and has a smooth, non-sticky surface feel. Referring to FIG. 1 of the drawing, the formed correction element 20 has a plastic film foundation 21 supporting the dry correction layer 22.

EXAMPLE 2 A latent adhesive correction element is produced by coating a web of 2.0 mil polyethylene terephthalate polyester film with about 11 pounds per ream (3300 sq.ft.) of the following hot-melt composition:

The wax extenders and adhesive resins are heated together at a temperature of about 160 F to form a uniform hot-melt. Then the Polymist powder spheres are added and mixed uniformly therewith to form a coatable hot-melt composition which is coated onto the polyester film as a uniform layer having a thickness of about 6 points and cooled to form the pressure-adhesive correction element.

According to another embodiment of the present correction process, the correction elements used may be produced by conventional encapsulation techniques whereby the pressure-flowable adhesive resin is the water-non-miscible, emulsifiable phase and the surface material is the ionizable hydrophilic colloid material which deposits around the adhesive resin in the form of pressure-rupturable capsules. Reference is made herein to US. Pat. No. 2,800,457 relating to suitable encapsulation techniques and to U.S. Pat. No. 2,986,477 relating to suitable pressure-adhesive encapsulated materials. Such materials are non-adhesive to the touch, due to the presence of the capsules which provide a nonadhesive surface casing enclosing the adhesive resin. In areas where the capsules are ruptured by typing pressure, the pressure-flowable adhesive resin is exposed for pressure-contact with the surface of the image to be removed. The degree of adhesion between the image and its support is much weaker than the degree of adhesion between the image and the pressure-flowable adhesive resin, whereby the image remains adhered to the latter and separates cleanly from the support or copy sheet when the correction element is separated from the latter.

EXAMPLE 3 A pressure-sensitive transfer element which is complementary to the correction elements of Examples 1 and 2 is produced by coating a web of 0.5 mil high density polyethylene film with the following composition:

The coated film is heated in a drying tunnel to evaporate the solvent and form a dry pressure-transferable imaging layer having a dry weight of about 2 pounds per ream. The coated film can be cut into sheet lengths and/or ribbon widths.

The coated film is used in the same manner as conventional carbon papers or typewriter ribbons to form images on ordinary copy paper but such images can be cleanly and completely removed from the copy paper by means of the present correction elements such as those produced according to Example 1 supra.

Referring to FIGS. 1 and 2 of the drawing, the imaged copy paper 10, having a paper foundation ll supporting the images 12 and 13 typed by means of the transfer element of Example 2, is positioned against the correction element 20 of Example 1 and the erroneous image 13 to be removed is overstruck with type bar 30 corresponding to center image 13, the correction element 20 being positioned therebetween with its latent adhesive layer 22 in surface contact with images 12 and 13. The impact of the type bar 30 forces the adhesive material within layer 22 into pressure contact with erroneous image 13 to form an adhesive bond therebetween, while the non-impressed areas of layer 22 retain a non-sticky surface which does not adhere to the images 12 in contact therewith. On separation of the sheets 10 and 20, the image 13 is completely and cleanly removed from copy sheet 10 and remains bonded to correction sheet 20 as removed image 13X, as shown by FIG. 2. Copy sheet 10 can be recompleted by typing a correct image in place of the removed image 13X using the same imaging composition.

As illustrated by FIG. 3, a so-called split correction ribbon 35 can be prepared according to the present invention by applying adjacent stripes of the present complementary correction composition 31 and imaging composition 32 to a common foundation. Correction composition 31 presents a non-sticky surface comprising the Polymist polymer spheres 33 so that the ribbon 35 can be wound on a spool in conventional manner similar to any other typewriter ribbon without the correction layer adhering to the back surface of the foundation. Also the split ribbon 35 can be fed within conventional ribbon guides without sticking thereto. This is also true of the present correction ribbons which carry a full coating of latent adhesive correction composition.

If desired, the present correction materials maybe produced by printing the correction composition onto the continuous foundation web in the form of spaced stripes or as discontinuous spaced applications so that the web may be cut into ribbons, tapes, tabs, sheets or other desired shapes without cutting through the pressure-adhesive layer. This is particularly advantageous in the case of several plies of superposed webs or sheets which are cut simultaneously into tabs. If a cut is made through the latent adhesive layer, the cut edges of the tabs stick together and the tabs are difficult to separate from each other. However, if at least one edge of each tab is free of the latent adhesive composition, the tabs can be separated from each other along that edge.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

We claim:

1. Process for producing latent adhesive pressuresensitive elements comprising the steps of producing a composition comprising a soft, pressure-flowable tacky adhesive resin, a substantial amount of an inert, nonadhesive surface material and a volatile vehicle, applying said composition to a flexible, pressure-deformable foundation, and evaporating said vehicle to form a latent adhesive layer in which said adhesive resin is present adjacent said foundation and said surface material is present at the surface of said layer and provides a discontinuous barrier stratum which is substantially nonadhesive to the touch but which is penetrable by said flowable adhesive resin under the effects of applied pressure.

2. Process according to claim 1 in which said inert, non-adhesive surface material comprises a synthetic resinous binder material which is incompatible with said adhesive resin and the evaporation of said volatile vehicle produces a microporous skeletal structure of said resinous binder material containing within the pores thereof said pressure-flowable adhesiveresin.

3. Process according to claim 1 in which said inert, non-adhesive surface material comprises polymer spheres having an average particle size between about 1 and 25 microns.

4. Process according to claim 1 in which said composition comprises said adhesive resin, an extender material comprising a synthetic resinous binder material which is not sticky or adhesive and which is compatible with said adhesive resin to form a resin blend having the desired degree of adhesiveness, and a finely-divided particulate material as said surface material, and the latent adhesive layer formed comprises said resin blend adjacent the foundation and said particulate material in the form of protrusions extending from said resin blend to form said discontinuous barrier stratum.

5. Latent adhesive pressure-sensitive elements comprising a flexible, pressure-deformable foundation sup porting a latent adhesive layer comprising a soft, pressure-flowable tacky adhesive resin and a substantial amount of an inert, non-adhesivesurface material, said adhesive resin being present adjacent said foundation and said surface material being present at the surface of said layer and providing a discontinuous barrier stratum which is substantially non-adhesive to the touch, said pressure-flowable adhesive resin being capable of flowing through said barrier stratum under the effects of applied pressure to render the surface of said layer adhesive in impressed areas.

6. A latent adhesive pressure-sensitive element according to claim 5 in which said surface material comprises finely-divided, particulate surface material.

7. A latent adhesive pressure-sensitive element according to claim 6 in which said surface material comprises polymer spheres.

8. A latent adhesive pressure-sensitive element present to claim 5 in which said latent adhesive layer comprises a base coating of said adhesive resin and a surface coating of said non-adhesive surface material.

9. A latent adhesive pressure-sensitive element according to claim 5 in which said layer comprises a microporous skeletal network of said non-adhesive surface material having within the pores thereof said adhesive resin.

10. A latent adhesive pressure-sensitive element according to claim 5 in which said latent adhesive layer comprises a unitary layer comprising said soft, pressure-flowable adhesive resin, an extender material comprising a synthetic resinous binder material which is not sticky or adhesive and which is compatible with said adhesive resin to form a resin blend having the desired degree of adhesiveness, and a finely-divided particulate material as said surface material, said particulate material protruding above the surface of said resin blend to form said discontinuous barrier stratum.

11. Process for producing latent adhesive pressuresensitive correction elements comprising the steps of producing a liquid composition comprising at least 10% by weight of the solids content as a soft, pressure-flowable adhesive resin, and at least 5% by weight of the solids content as an inert, non-adhesive, particulate surface material, applying said liquid composition to a flexible, pressure-deformable foundation, and causing it to solidify to form a latent adhesive layer in which said adhesive resin is present adjacent said foundation and at least 10% of the weight of said surface material projects beyond the surface of said layer and provides a barrier stratum which is substantially non-adhesive to the touch but which is penetrable by said flowable adhesive resin, at ambient temperatures, under the effects of applied pressure.

12. Process according to claim 11 in which said liquid composition comprises a volatile liquid solvent for said adhesive resin, and the layer is caused to solidify by evaporation of said solvent.

13. Process according to claim 11 in which said liquid composition also comprises an extender binder material which is substantially less adhesive than said adhesive resin and which provides a mixture having the desired degree of adhesiveness.

14. Process according to claim 13 in which said extender binder material comprises a wax, said liquid composition is a hot-melt composition and said layer is caused to solidify by cooling.

15. Latent adhesive pressure-sensitive correction elements comprising a flexible, pressure-deformable foundation supporting a latent adhesive layer comprising at least about 10% by weight of a soft, pressure-flowable adhesive resin and at least about 5% by weight of a particulate, inert, non-adhesive surface material containing at least about 10% of theweight thereof in the form of large particles'having a greater thickness than the thickness of said adhesive layer, said adhesive resin being present adjacent said foundation and said large particles of surface material projecting beyond the surface of said layer and providing a barrier stratum which is substantially non-adhesive to the touch, said pressure-flowable adhesive resin, at ambient temperatures, being capable of flowing through said barrier stratum under the effects of applied imaging pressure to render the surface of said layer adhesive in impressed areas.

16. A latent adhesive element according to claim 5 in which said particulate surface material comprises poly- 13 mer spheres.

17. A latent adhesive element according to claim 15 in which said layer comprises an extender binder material which is substantially less adhesive than said adhesive resin and which provides a mixture having the desired degree of adhesiveness.

18. A latent adhesive element according to claim 17 in which said extender comprises a wax and said adhesive layer is applied as a hot-melt composition.

19. A latent adhesive element according to claim 17 in which said extender comprises a resin and said adhesive layer is applied as a solvent coating.

20. A latent adhesive element according to claim 15 comprising a stripe of said latent adhesive layer and an adjacent stripe of pressure-transferable imaging composition, said imaging composition being imagewise pressure-transferable to a copy sheet under the effects of imaging pressure and said latent adhesive layer being capable of substantially completely removing said inagewise imaging composition from said copy sheet when impressed thereagainst with a corresponding imaging pressure.

21. Process for the selective and complete removal of an erroneous typed image from a copy sheet having said image thereon in association with a multiplicity of other images typed from the same imaging composition which comprises resinous binder material and pigment, said process comprising positioning over said images a latent adhesive correction element comprising a pressure-deformable foundation supporting a non-sticky latent adhesive layer which contains at least 10% by weight of an adhesive resin, which is pressure-flowable at ambient temperatures, and a non-adhesive surface material which provides a barrier stratumat said surface and renders said layer non-adhesive to the touch, and typing against the back of said foundation with a type face corresponding to the erroneous image to be removed and in a location corresponding to the position of said erroneous image to cause said latent adhesive correction element to be pressed against said erroneous image and to cause said adhesive resin to flow through said barrier layer and adhere to said erroneous image, and separating said correction element from said copy sheet whereby said erroneous image remains adhered to the former and is stripped from the latter without the correction sheet adhering to or disturbing the other images on the copy sheet.

22. Process according to claim 21 in which the correction element is sufficiently transparent that the images on the copy sheet can be read therethrough to facilitate visual segregation of the erroneous image.

23. Process according to claim 21 in which said latent adhesive layer comprises pressure-rupturable capsules of said surface material containing therein said pressure-flowable adhesive resin.

24. Process according to claim 21 in which said surface material comprises solid particles which project beyond the surface of said pressure-flowable adhesive resin.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 5,92A,728

DATED December 9, 1975 |NVENTOR( Albert E. Brown, Allan T. Schlotzhauer and Douglas A. Newman It ts certrrled tha error appears In the above|dent|f|ed patent and that sard Letters Patent are hereby corrected as shown below;

Column 1, line A5, "not" inserted after do column 12, lines 1 and 2 (Claim 8) Fpresent" should read according column 12, line 67 (Claim 16) "5" should read 15 Bigncd and Sealed this thirteenth D 21y Of April 1 9 76 [SEAL] A ttesr:

RUTH C. MASON C. MARSHALL DANN Atlosting Officer ('mnmissr'mu'r ujlalwz rs and Trademarks 

1. Process for producing latent adhesive pressure-sensitive elements comprising the steps of producing a composition comprising a soft, pressure-flowable tacky adhesive resin, a substantial amount of an inert, non-adhesive surface material and a volatile vehicle, applying said composition to a flexible, pressure-deformable foundation, and evaporating said vehicle to form a latent adhesive layer in which said adhesive resin is present adjacent said foundation and said surface material is present at the surface of said layer and provides a discontinuous barrier stratum which is substantially non-adhesive to the touch but which is penetrable by said flowable adhesive resin under the effects of applied pressure.
 2. Process according to claim 1 in which said inert, non-adhesive surface material comprises a synthetic resinous binder material which is incompatible with said adhesive resin and the evaporation of said volatile vehicle produces a microporous skeletal structure of said resinous binder material containing within the pores thereof said pressure-flowable adhesive resin.
 3. Process according to claim 1 in which said inert, non-adhesive surface material comprises polymer spheres having an average particle size between about 1 and 25 microns.
 4. Process according to claim 1 in which said composition comprises said adhesive resin, an extender material comprising a synthetic resinous binder material which is not sticky or adhesive and which is compatible with said adhesive resin to form a resin blend having the desired degree of adhesiveness, and a finely-divided particulate material as said surface material, and the latent adhesive layer formed comprises said resin blend adjacent the foundation and said particulate material in the form of protrusions extending from said resin blend to form said discontinuous barrier stratum.
 5. Latent adhesive pressure-sensitive elements comprising a flexible, pressure-deformable foundation supporting a latent adhesive layer comprising a soft, pressure-flowable tacky adhesive resin and a substantial amount of an inert, non-adhesive surface material, said adhesive resin being present adjacent said foundation and said surface material being present at the surface of said layer and providing a discontinuous barrier stratum which is substantially non-adhesive to the touch, said pressure-flowable adhesive resin being capable of flowing through said barrier stratum under the effects of applied pressure to render the surface of said layer adhesive in impressed areas.
 6. A latent adhesive pressure-sensitive element according to claim 5 in which said surface material comprises finely-divided, particulate surface material.
 7. A latent adhesive pressure-sensitive element according to claim 6 in which said surface material comprises polymer spheres.
 8. A latent adhesive pressure-sensitive element present to claim 5 in which said latent adhesive layer comprises a base coating of said adhesive resin and a surface coating of said non-adhesive surface material.
 9. A latent adhesive pressure-sensitive element according to claim 5 in which said layer comprises a microporous skeletal network of said non-adhesive surface material having within the pores thereof said adhesive resin.
 10. A latent adhesive pressure-sensitive element according to claim 5 in which said latent adhesive layer comprises a unitary layer comprising said soft, pressure-flowable adhesive resin, an extender material comprising a synthetic resinous binder material which is not sticky or adhesive and which is compatible with said adhesive resin to form a resin blend having the desired degree of adhesiveness, and a finely-divided particulate material as said surface material, said particulate material protruding above the surface of said resin blend to form said discontinuous barrier stratum.
 11. Process for producing latent adhesive pressure-sensitive correction elements comprising the steps of producing a liquid composition comprising at least 10% by weight of the solids content as a soft, pressure-flowable adhesive resin, and at least 5% by weight of the solids content as an inert, non-adhesive, particulate surface material, applying said liquid composition to a flexible, pressure-deformable foundation, and causing it to solidify to form a latent adhesive layer in which said adhesive resin is present adjacent said foundation and at least 10% of the weight of said surface material projects beyond the surface of said layer and provides a barrier stratum which is substantially non-adhesive to the touch but which is penetrable by said flowable adhesive resin, at ambient temperatures, under the effects of applied pressure.
 12. Process according to claim 11 in which said liquid composition comprises a volatile liquid solvent for said adhesive resin, and the layer is caused to solidify by evaporation of said solvent.
 13. Process according to claim 11 in which said liquid composition also comprises an extender binder material which is substantially less adhesive than said adhesive resin and which provides a mixture having the desired degree of adhesiveness.
 14. Process according to claim 13 in which said extender binder material comprises a wax, said liquid composition is a hot-melt composition and said layer is caused to solidify by cooling.
 15. Latent adhesive pressure-sensitive correction elements comprising a flexible, pressure-deformable foundation supporting a latent adhesive layer comprising at least about 10% by weight of a soft, pressure-flowable adhesive resin and at least about 5% by weight of a particulate, inert, non-adhesive surface material containing at least about 10% of the weight thereof in the form of large particles having a greater thickness than the thickness of said adhesive layer, said adhesive resin being present adjacent said foundation and said large particles of surface material projecting beyond the surface of said layer and providing a barrier stratum which is substantially non-adhesive to the touch, said pressure-flowable adhesive resin, at ambient temperatures, being capable of flowing through said barrier stratum under the effects of applied imaging pressure to render the surface of said layer adhesive in impressed areas.
 16. A latent adhesive element according to claim 5 in which said particulate surface material comprises polymer spheres.
 17. A latent adhesive element according to claim 15 in which said layer comprises an extender binder material which is substantially less adhesive than said adhesive resin and which provides a mixture having the desired degree of adhesiveness.
 18. A latent adhesive element according to claim 17 in which said extender comprises a wax and said adhesive layer is applied as a hot-melt composition.
 19. A latent adhesive element according to claim 17 in which said extender comprises a resin and said adhesive layer is applied as a solvent Coating.
 20. A latent adhesive element according to claim 15 comprising a stripe of said latent adhesive layer and an adjacent stripe of pressure-transferable imaging composition, said imaging composition being imagewise pressure-transferable to a copy sheet under the effects of imaging pressure and said latent adhesive layer being capable of substantially completely removing said inagewise imaging composition from said copy sheet when impressed thereagainst with a corresponding imaging pressure.
 21. Process for the selective and complete removal of an erroneous typed image from a copy sheet having said image thereon in association with a multiplicity of other images typed from the same imaging composition which comprises resinous binder material and pigment, said process comprising positioning over said images a latent adhesive correction element comprising a pressuredeformable foundation supporting a non-sticky latent adhesive layer which contains at least 10% by weight of an adhesive resin, which is pressure-flowable at ambient temperatures, and a nonadhesive surface material which provides a barrier stratum at said surface and renders said layer non-adhesive to the touch, and typing against the back of said foundation with a type face corresponding to the erroneous image to be removed and in a location corresponding to the position of said erroneous image to cause said latent adhesive correction element to be pressed against said erroneous image and to cause said adhesive resin to flow through said barrier layer and adhere to said erroneous image, and separating said correction element from said copy sheet whereby said erroneous image remains adhered to the former and is stripped from the latter without the correction sheet adhering to or disturbing the other images on the copy sheet.
 22. Process according to claim 21 in which the correction element is sufficiently transparent that the images on the copy sheet can be read therethrough to facilitate visual segregation of the erroneous image.
 23. Process according to claim 21 in which said latent adhesive layer comprises pressure-rupturable capsules of said surface material containing therein said pressure-flowable adhesive resin.
 24. Process according to claim 21 in which said surface material comprises solid particles which project beyond the surface of said pressure-flowable adhesive resin. 